The project consists of five different complexes, which all have solar energy measures integrated in building facade. Still the technology and use of the solar systems varies. Complexes 1-3 have additional power supply in the shape of PV-modules, which are integrated with the ventilation system. Complexes 2-3 moreover have solar collectors for hot water and space heating purposes.

Complex 1 - Tøndergade 3-3A 
PV-modules with a total area of 32m² and a peak power supply of 1.34 kW are placed around the windows as an integrated part of a facade renovation of the south facade of the building. In this project, the use of PV is also combined with the ventilation system as air for ventilation is pre-heated behind the panels. The ventilation system has heat recovery and low energy ventilator fans.

Highlights:

• Additional insulation and low-energy windows.
• Central placing of the radiators.
• Central heat recovery systems.
• Two central heat recovery units, placed in the attic, covering 10 apartments each. Heat surfaces that give extra heat to the ventilation air.
• Building integrated amorphous PV-modules from Fortum in the facade.
• The living rooms facing the courtyard have a 6 m² heated glazed patio each. The window parapets are covered with 60 m² amorphous PV-modules. The PV-modules are utilised in a hybrid solution where the ventilation air is preheated behind the PV-modules, which also has the effect that the cooled PV-modules get a higher yield.

Complex 2 – Tøndergade/Sundevedsgade
Here the use of PV-modules is based on the PV-Vent technique. The objective of the PV-Vent project is to develop low cost, but high efficiency PV-powered ventilation systems for apartment blocks, where PV modules are integrated in an architectural acceptable way in facades, gables and roofs. The use of ventilation fans with new and reliable DC-motors enables the photovoltaic modules to cover part of the electricity demand directly, so that the electricity demand for the system is only about 25-40 W per dwelling, which equals to an electricity consumption of only 200-300 kWh per year.

A thermal solar collection system is also installed in this complex. It is a combined system for domestic hot water and space heating. The solar collector is an air collector type in which the heated air from the collector is transferred to an air/water heat exchanger placed in the roof space. A water piping system transfer the solar heat to a buffer storage in the boiler room located in the basement. The advantage of using air collectors is that there are no problems with freezing or boiling.

Finally the integrated solar facade enables the inclusion of glass patios for the dwellings.

Highlights:

• PV-modules. 60 m² mains connected crystalline PV-modules from Gaia Solar have been mounted on the two original stair turrets. Preheating of the air in the stair turrets cools the back of the PV-modules and in this way the transmission loss between the stairs and the apartments is reduced.
• Solar heating system. On the roof there is a solar heating system from Batec Solar Heating that heats the domestic hot water. The total area is 35 m².
• Heat recovery. In the attic there are two high efficient counter flow heat recovery units from EcoVent, which covers 10 apartments each.
• Central placing of radiators gives saving on investment costs.
• Double windows with hard covering.
• Solar energy optimised sunspaces with overheating protection.
• Heat recovery of the ventilation air has in this way reduced the heat loss of approx. 20 kW; equal to approx. 20 W per m² heated area.
• 82 DKK/m² has been saved by use of a solution with centrally placed versus conventionally placed radiators. In a 70-m² apartment this is equal to a total saving of the investments of 5,700 DKK, which are primary coming from the use of centrally placed riser pipes.

Complex 3 - Sundevedsgade 26-28
This complex is equipped with 39m² of PV-modules with a total peak power of 3 kW, which are situated vertically on the staircase facade facing the courtyard with a south/west orientation. The PV-modules are ventilated in the air gab between modules and the wall in a way that transfer the preheated air to the staircase. The airflow through the staircase is forced by natural ventilation.

This complex also has a thermal solar heating system designed for domestic hot water. The solar collectors make up a roof-integrated system with a storage tank of 1.6 m³ in the boiler room on the ground floor. The piping between the collector and storage tank goes through an old chimney, which is not used anymore.

Highlights:
The project includes the rehabilitation of 20 apartments. The following energy saving measures are included in the project:

• Air solar collector. A 19-m² air solar collector has been mounted on the roof, and heats a central storage tank in the basement, which is also connected to the district heating system.
• A new solar wall design with an integrated heat recovery unit that is also connected to the district heating system is used for 12 apartments. The only 25 cm thick counter flow solar wall has been built with frosted glass and PV-modules as covering coat. The heat recovery unit has been placed inside the solar wall. This innovative unit from EcoVent contains the counter flow heat recovery unit, sound absorber and ventilation fans. The complete heat recovery system is high efficient and has a very low electricity consumption. These systems form part of the EU/Joule project PV-VENT together with the PV-modules. A built-in damper in the solar wall that secures against too high temperatures.
• Ventilation with heat recovery for eight apartments. The corner apartments cannot be connected to a solar wall and individual counter flow heat recovery units with 85% efficiency have therefore been placed here also as individual systems. The ventilation systems in these apartments have been made as real air heating systems by means of heating surfaces that are heated by district heating. There is also a traditional but centrally placed radiator system to cover peak load.
• PV-modules. The PV-modules form part of the solar wall and the produced electricity is used directly in the heat recovery unit by help of a so-called PV-mixer. There are approx. 1-m² PV-modules per apartment.
• Water heat exchangers. The heating is supplied from the central storage tank in the basement, which is partly supplied with district heating and partly with heat from the air solar collector. The heat is in this way supplied to the apartments for both room heating and domestic hot water via only one duct, which reduces the heat loss. The heating of the water takes place via individual domestic hot water heat exchangers that also secure against problems with bacteria.
• South oriented sun-protected sunspaces for each apartment and improved daylight function.

General information on the technologies:
PV-modules
Solar collector air systems
Solar collector water systems

Suppliers of technology:
As the solar systems are heavily integrated, there have been several companies involved in the project. The PV-modules are manufactured by Shell Solar in co-operation with Gaia Solar that designs and provides the systems. The solar collector systems are entirely manufactured and provided by the Danish solar company, Batec. 

PV-modules:
Gaia Solar A/S
Gaia Solar develops, produces and markets PV-systems based on the modules from Shell Solar, and offers products and know-how in building integrated solar power.
Address: Hammerholmen 9-13
DK-2650 Hvidovre
Phone: +45 36777976
e-mail: info@gaiasolar.dk
www.gaiasolar.dk (Co-operative with Shell Solar: www.shellsolar.com)

Solar collector systems:
Batec A/S
Batec designs, manufactures and provides total air or water based solar collector systems of all sizes for building integrated applications both domestically and internationally. Moreover the company manufactures certain components for other solar collection providers worldwide.
Address: Danmarksvej 8
DK-4681 Herfølge
Phone: +45 56275050
e-mail: admin@batec.dk
www.batec.dk